What is the cross product of #(4 i + 4 j + 2 k)# and #(i + j -7k)#?

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Answer 1 · 2016-12-18T18:26:07

The vector is #=〈-30,30,0〉#

The cross product is obtained from the determinant

# | (hati,hatj,hatk), (4,4,2), (1,1,-7) | #

#=hati(-28-2)-hatj(-28-2)+hatk(0)#

#=〈-30,30,0〉#

Verification

we do a dot product

#〈-30,30,0〉.〈4,4,2〉=(-120+120+0=0)#

#〈-30,30,0〉.〈1,1,-7〉=(-30+30-0)=0#